The proposed research will exploit an extremely valuable data source to study fertility in the City of Munich between 1850 and 1914. Munich's police registration records (Polizeimeldebogen or PMBs) contain 1ife-cycle histories of most individuals born in or who moved to Munich during this period. Examination of a small pilot sample from the PMBs documents their rich demographic information and rare data on migration histories, socioeconomic status, and wealth. The research project will collect a sample of suitable size to take full advantage of the richness of this source. We will then use the sample to test theories about the role of rural-urban migration, urbanization, and socioeconomic change in the European fertility transition. The sample will also be valuable for the study of infant and child mortality, migration per se, and other topics; we will make the sample public as soon as we have completed our own research. While historical demographers have undertaken many careful studies of the fertility transition in Europe, our research has two novel features that have the potential to fill several gaps in scholars' understanding of the European fertility transition. Few historical studies have been able to employ sources as rich as the PMBs; our data will support precise tests of often-discussed hypotheses about the role of migration, socioeconomic change, and urbanization in fertility decline. Ours is also the first individual-level study of fertility in an urban German population. Urbanization was particularly rapid in late nineteenth-century Germany; this and other distinctive features of German demographic and socioeconomic development make it an important instance in which to test general models formulated in other contexts.